1. FIELD OF THE INVENTION
The present invention relates to a coating composition for forming alcohol-insoluble nylon coating films.
2. DESCRIPTION OF THE PRIOR ART
As alcohol-soluble nylons generally used as surfacefinishing agents or adhesives, there may be mentioned (1) nylon copolymers comprising monomer units of two, three or four members selected from the group consisting of nylon 6, nylon 6.6, nylon 6.10, nylon 11, nylon 12 and nylon 6.12, and (2) N-alkoxymethylated nylons. In general, the nylon copolymers are superior to N-alkoxymethylated nylons in mechanical or physical properties. On the other hand, the N-alkoxymethylated nylons can be insolubilized in alcohol by adding an acid thereto.
The alcohol-soluble nylon copolymers are thus soluble in a lower alcohol such as methanol or ethanol or a solvent mixture of such a lower alcohol and a chlorinated hydrocarbon or aromatic hydrocarbon such as trichloroethylene or toluene.
The object to be coated is dipped into the solution thus obtained or the solution is applied to the object with a roll or brush to form a coating thereon and then the object is heated to remove the solvent, thereby forming the nylon coating film. The film thus formed has an excellent abrasive resistance and adhesive strength to the object.
Further, nylon coating films have a special desirable touch which cannot be obtained by other materials, and, therefore, they have been used widely as surface treating agents or adhesives for textiles, woods, papers, leathers, rubbers and metals. However, the coating films thus formed from the alcoholsoluble nylon copolymers are reversibly soluble in alcohols and, accordingly, they cannot be used for coating an object which will be contacted with alcohols. Under the circumstances as above, many attempts have been made to insolubilize the coating films of alcohol-soluble nylon copolymers.
There has been proposed a process wherein a light-sensitive cross-linking agent such as N,N-methylene-bisacrylamide is added to a coating composition and it is then exposed to ultraviolet rays to insolubilize the same, and a process wherein melamine is added to the composition and it is then heated to insolubilize the same. However, these prior processes have been troublesome, because treatment with ultraviolet rays is required or the temperature employed in the insolubilization by heating is sometimes excessively high.